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Bandwidth

If you're working with network cameras and recorders, you will ultimately come across Bandwidth. We recommend understanding bandwidth and taking it into consideration before any IP surveillance setups.

What is Bandwidth?

Video surveillance systems, depending on their size, can consume large amounts of bandwidth. Because of this, networks that cannot sustain the demand can lead to a wide array of problems such as delayed video feeds. Bandwidth itself is simply the rate that data is transferred or how much data is in within a frequency band. If you have gone to a speedtest website, you will see your upload and download speeds. In correspondence with download and upload speeds, it is measuring how much bandwidth being received and sent by your computer.

How is bandwidth measured?

There are two common measurements for bandwidth, bits and bytes. 1 Byte is the equivalent of 8 bits. For larger amounts of bandwidth, they are expressed in kilobits, megabits, and gigabites.

Kilobits: Kilobits is expressed in the thousands. 100,000 bits would be 100 kilobits or 100kb/s.

Megabits: Megabits is expressed in the millions. 1,000,000 bits would be 100 megabits or 100mb/s.

Gigabits: Gigabits is expressed in the billions. 1,000,000,000 bits would be 1 gigabit or 1gbs.

If you read some of the definitions above, we said "100,000 bits would be 100 kilobits or 100kb/s." You might be wondering what "/S" stands for. For reference, think about how fast you drive to work, it might be 50 miles per hour, or 50mph. 50mph would be your rate over time. In retrospect to bandwidth, it would be called the bitrate. Therefore, 100kb/s is 100 kilobits per second, meaning 100 kilobits of data are being transmitted in a second.

Bandwidth for Cameras

Bandwidth is not the same for every camera. Each surveillance camera has its own bandwidth demands. Some may need only 1mb/s and others need 5b/s. If you would like to learn how to calculate how much bandwidth is needed in total, click here for instructions on using the Platinum Toolset -- insert link

Factors Affecting Bandwidth

The following factors below affect how much bandwidth a camera requires

Resolution: While cameras and videos are capable of achieving extremely high resolutions, users need to be considerate of the costs that come with such high definition videos. As you increase the resolution, you also increase the number of pixels on the screen. Therefore, you increase the bandwidth demand.

Frame rate: Frame rate, also known as frames per second. To go over it briefly, frames per second is the frequency that consecutive images are shown. Consider drawing multiple images of a person walking per page on a flipbook. If you flip through the pages, it looks as if that person is walking in real time. However, if you only drew a few pages, it doesn't look too realistic. If you drew dozens upon dozens of images, the walking motion looks more fluid and realistic. Note that it required more pages or "frames" to increase the fluidity of the motion. This can be applied to bandwidth demand as well. Increased frame rates have more frames but also need more bandwidth at the same time.

Scenery: The scenery of the video feed itself can have an adverse effect on bandwidth demands. A security camera facing an empty lot may only require 1mb/s but a camera in a shopping mall may need 5mb/s. Consider that an empty lot has little to no activity. Therefore, there would be little to no changes between each frame, meaning very little video data would have to be transmitted for each frame. In the case of a mall however, there would be significant changes per frames due to the number of people walking around in a mall. Significant changes in a frame require much more data to be transmitted than frames without any changes.

IR or infrared: As available light decreases, bandwidth usage may increase for some cameras. Consider how the image sensors work inside cameras in the first place. They require light to make pictures or videos. As there is less light, some cameras will need to increase the video signal in low light setting. This creates noise in the process, causing the increase in bandwidth usage due to the frequent changes in scenery caused from noise.

Video Compression Standards: To address the significant consumption of bandwidth, recorders and cameras support video compression. The compression standards or codecs determine how the video recorded is packaged before the data is transmitted. This reduces not only the size of the file but also the amount of bandwidth needed to transmit it. Keep in mind there are no static numbers that guarantee figures such as 90% bandwidth savings due to the numerous factors we have listed above. To learn more about video compression standards, click here <-- insert link.

IP Versus TVI in Bandwidth Consumption

We recommend you understand the differences between the setups of IP surveillance systems and TVI surveillance systems before continuing here. If you would like to learn more, click here <-- insert link.

IP and TVI surveillance systems not only have different types of setups but they also have different bandwidth demands. TVI or Analog cameras typically do not consume bandwidth because they are directly connected to the recorders themselves. In that case, only the recorder would consume bandwidth. IP cameras however need to transmit data to the recorder and therefore consume network bandwidth unless they are directly connected to the recorder.

Now consider a scenario in which there are multiple cameras spread out across a few buildings but only one recorder. These IP cameras would consume significant bandwidth unless you had a recorder in each building for its respective cameras. This is because the recorders themselves act as a buffer to reduce the bandwidth demand.